Variable photographic mask for maintaining constant proportions of a visible area



June 24, 1941. KRQMHQLZ 2,246,920

VARIABLE PHOTOGRAPHIC M sK FOR MAINTAINING CONSTANT PROPORTIONS OF AVISIBLE AREA Filed March 15, 1940 2 Sheets-Sheet 1 ATTORNEYS June 24,1941. KRQMHOLZ 2.246,9Z0

VARIABLE PHOTOGRAPHIC MASK FOR MAINTAINING CONSTANT PROPORTIONS OF AVISIBLE AREA Filed March 15, 1940 2 Sheets-Sheet 2 AT .7' 019M345.

Patented June 24, 1941 VARIABLE PHOTOGRAPHIC MASK FOR MAINTAININGCGNSTANT PROPORTIONS OF A VISIBLE AREA Louis L. Kromholz, White Plains,N. Y.

Application March 15, 1940, Serial No. 324,078

(Cl. 33l7) filaims.

My invention has been especially devised and is here described asintended for use in making photographic enlargements from prints orfilms, but it may be applied in any instance in which a selected area ofa surface is to be reproduced or projected, either with or withoutenlargement, the object of my invention being to sheet the selectionfrom the print of an area of dimensions proportionate to those desiredon the reproduction, whatever be the size of the area selected.

When an enlargement is to be made of a print or negative, it is oftendesired to confine the reproduction to a part, sometimes of very limitedarea, of the original picture, either because it will reproduce betteror will give a more artistic result than a reproduction of the whole, orbecause the interest is confined to that area, or because it is desiredto show an object or individual in a slightly altered pose from that ofthe original, or for other reason. Enlargements are usually to certainstandard dimensions-eight byten inches being a favored size andproportion. The selected area should conform, on its smaller scale, totheproportions, the relation of height to width, of the proposedenlargement or other reproduction.

It is now a well-known practice, when an enlargement is to be made ofpart of a print or film, to employ two masks, each mask being anL-shaped plate of about the shape of a machinists square. The print orother matter to be duplicated is laid on a flat surface and one of themasks is laid upon it with its inside angle defining the selected areaon two sides and masking all of the print outside the inner edge of themask. The other mask is inverted over the print with its inside anglefacing that of the first mask, and is shifted thereon until the secondmask defines the remaining two sides of the part to be reproduced, andmasks all of the print on those sides which are not to be reproduced.There is thus enclosed by the two masks an uncovered portion of theprint, whose size and shape depend on the adjustment of the L-shapedmasks toward or away from'each other, and by great.

adjustment of one mask upon the other when they are being shifted oneover the other until a position is reached which includes, between theopposed angles of the two masks, all of the print which is to beenlarged or duplicated, so that a fixed ratio of side to end of the areaof the print which is being isolated will be maintained. This is done byguiding or controlling the movement of one mask relatively to the otherso that the movement is in or parallel to a line joining the-apices ofopposite angles of the two masks. The masks thus comprise a.self-contained unit for demarcating a selected rectangw,

lar portion of a photograph or the like, so that the duplicate, as forenlargement, of the selected area may be made, of predeterminedproportional dimensions.

The accompanying drawings illustrate vention in two forms- Figure 1showing in perspective one form of the masks in separated condition, and

Figure 2 (in perspective also) the same combined for use.

Figure 3 is a sectional view taken in the direction indicated by thearrows 3--3, Figure 2.

Figures 4 to 8 illustrate another formof the invention, Figure 4 showingit in perspective, Figure 5 in plan, Figure 6 in section on the linei3--6, Figure 5, and Figure 7 in section on the line 7-1, Figure 5.Figure 8 is a detail sectional view on the line 8t, Figure 5.

Figure 9 is a view of the print as marked for enlargement.

My invention does not need a stationary table for supporting the printor other matter to be enlarged. In the form of the invention shown inFigures 1 to 3, the instrument comprises two relatively movable masks Aand B, of which A, conveniently held by the left hand in anapproximately constant position, I refer to as the holding or stationarymask, while B, referred to herein as the moving or covering mask, may beheld conveniently in the right hand and be moved over the mask A, tocontrol the dimensions of the part of a print or negative selected forenlargement. The mask A has a one-piece imperforate, preferablyrectangular, back sheet I of stiff, light material, cardboard forexample. I provide means to hold adiustably on the back i a print ornegative 2, a portion'oi which is to be selected for enlargement. Thisholding means may conveniently be a cardboard upper or front sheet 3 ofoutside dimensions equal to back sheet I. Enough of the material ofsheet 3 is removed to form windows 4, 5, leaving vertical and horimyinzontal masking portions 6, I and an attaching strip 8. These parts mayhave conveniently about the relative sizes shown. The outside verticaledges of the portions 6 and 8 are cemented to the corresponding edges ofthe back sheet l, preferably with the interposition at each edge ofspacer strips 9, l 0, so that the central portions of the sheets I and 3between the strips 9, HI (indicated by the dotted lines H, H onFigure 1) will have enough space between them to ellowa print to beinserted and shifted about-but not so loosely but that the print will belightly held by friction in any position to which it may be moved. BandI and the upper part of 6, with their rectangularly-disposed edges I3,14, form an L which performs practically the same function as thecorresponding L-shaped mask used with the area-determining method abovereferred to as that now practiced, here, however, being united to theback sheet I. They have the additional function of cooperating with thelatter in holding the print to a position to which it is set. The printis adjusted under the edges l3, M by manipulating it through the window4 (or window 5 if the print is of strip form) until all the undesiredpart of the print beyond said edges is masked by the portions 6, 1 ofthe sheet 3. The setting of the print may be upright, or slightlyrotated, if it be desired to alter the pose of the figure or partselected for enlargement. Figure I illustrates a print so positioned asto mask lower and left-hand parts of the print. It is obvious that formanipulating the form and size of print here shown, the window 5 is notessential.

Cooperating with the mask A is the cover mask B, which is a sheet 15 ofcardboard or other material, preferably of approximately the size ofmask A and provided with a rectangular window l6 formed with edgesparallel to those of the mask B, and it may be moved over the mask A sothat the inverted L, formed-by the portion of the sheet above and to theright of the window l5, and the L-shaped part of mask A exposed betweenthem only that portion of the print which it is desired to reproduce inthe enlargement, as for instance the part of the print appearing inFigure 2 through window 4.

Movement ofthe mask B over the mask A in or parallel to a line diagonalto the apices of opposite angles a and b on respective masks A and B,will alter the size without changing the proportional dimensions of theunmasked area.

Such a controlled movement is accomplished ac- 1 face of mask A asindicated at I! and a similar guide line l8 on mask B. By always keepingline l8 directly over line i! when the mask B is moved on mask A, thecorrect shape of the exposed part of the print will be maintainedwhatever be the distance apart of the masks. Instead of depending onguide lines whose register must be maintained by the operator, th twomembers may be positively engaged as by tongue on mask A and groove onmask B, or vice versa, taking the place of the lines l1 and I8, toinsure that the mask B shall be positively maintained in the right path.When the isolation has been made of the area selected for enlargement,the outline is marked on the print, as by running a red pencil (or othercolor contrasting with the color of light used) around the inner edgesof the masks as indicated by the rectangular dotted line 19 on Figures 2and 9, and this line enables the tions.

setting of the enlarging camera so as to reproduce, exactly toproportion, the selected area.

Means, as for example hole 25, in the corner of the instrument, may beused to hang it up.

The instrument shown in Figures 4 to 8 carries this idea of positiveguidance of the upper mask further, and illustrates additional modifica-The construction shown has stability whilesmaintaining light weight.Here the stationary mask A has preferably a back plate I of translucentsheet material, such as Formica, to better adapt the instrument to usewith photographic negatives. A front sheet 3 of cardboard or the like isconnected at its lateral edges to thelateral edges of back plate, i bycement or by bolts or rivets 20 which fasten side wood. metal or plasticguide rails 2| to the lateral edges of back plate I, spacers 9 HIseparating the back plate and front plate sufliciently to permit entryof the print between them and allow it to be moved about in the pocketso constituted and yet be held lightly by friction in any position towhich it is shifted. A window 4*, whose lower edge is a right angle, iscut in the upper or front sheet 3 The upper mask B comprisesthe sheet Iii of cardboard or the like material with its four sides stiflened by aframe 23 which may be of wood, or other suitable material, and the siderails 23 of which lie in contact with and are guided by the rails 2 I.The lateral edges of plate l5 project beyond the side rails 23 of theframe to enter the grooves 22 in the inner edges of rails 2| and holdthe upper mask in close but light contact with the plate 3 of the lowermask. The

sheet l5 has a window Mi and the two windows 4 and IS are so placed andoriented with respect to the guide rails 2| that a line diagonal to theopposite angles a and b of the two windows, if produced, will meet theapex of the opposite angle of window I6 and of course, it produced inthe opposite direction, will meet the opposite anglenot shown-of window4 and movement of the upper mask A in the path restricted by the rails21 will cause an expansion of the area of the print exposed to be alwaysconstant in the proportion of its dimensions. When the adjustment of thetwo masks has achieved the desired extent of unmasked area, the outlineis marked as before by running a line on the print around the edges ofthe window to preserve for use in the enlarging operation the exact partof the print desired. The area so marked, irrespective of dimensions,will enlarge to the proportions of the standard size photographic paper.

A scale,as 24, may be marked upon the inner edge of window 4, to informthe operator as to the size of the selected area on each side.

'There need be. only one operative angle on mask A and one on mask B,and these are interior angles arranged oppositely so as to presentbetween them a visible area of the print or negative of size dependingon the distance apart to sary, as are also all of the windows beyondthat strengthen the structure. The use of the terms right and leftrefers to an instrument constructed for a right-handed person. It may bedesirable to reverse certain parts of the mask for a left-handed person.

Except where they otherwise specifically appear, the words print,negative and positive are used interchangeably in this specification.

I claim:

1. A self-contained apertured unit for demarcating a selected portion ofa photograph or the like, comprising in combination a pair ofdemarcating plates, one or said plates having upon its outer marginstracks through which it is shiitably interconnected with and positivelyguides the other plate, without restricting relative movement betweenthe plates as a unit and the photograph, in the plane of the photograph;said plates having portions through which they overlap, constructed withreentrant edges forming rectangular recesses therein and assembled withsaid recesses diagonally aligned and composing a rectangular spaceconstituting the aperture of the'unit, and the said tracks beingpositioned to restrict the shifting of the plates with respect to eachother to a direction parallel with a diagonal of said rectangular space.

2. A self-contained unit for demarcating a selected rectangular portionof a photograph or the like, comprising in combination, a pair of plateshaving portions through which they overlap upon and slide relatively toone another; said portions being constructed with reentrant edges thatdefine rectangular recesses therein; said plates being assembled withsaid recesses presented toward each other, and diagonally aligned sothat together said recesses compose a rectangular aperture through theunit; and one of said plates having means engaging the other to holdthem together as a unit for unrestricted relative movement between thephotograph and 5 the unit and to positively guide the sliding movementof one plate with respect to the other in a direction parallel with adiagonal of the said rectangular aperture.

3. In a unit for demarcating a selected portion of a photograph and thelike, the combination of a back-plate, an aperture unit and meansuniting said back-plate and aperture unit with a space between them intowhich the photograph or the like may be introduced with treedom to movein any direction parallel with the aperture unit; said aperture unitcomprising a pair 01' demarcating plates having portions through whichthey lap upon and slide relatively to one another, constructed withreen- 0 trant edges that define in said portions respectively,rectangular recesses opposed to each other on a diagonal line andtogether composing a rectangular space that constitutes the aperture ofthe aperture unit; the relative sliding movement of the demarcatingplates being parallel with said diagonal line.

4. A unit as described in claim 3, in which the .back plate is made of asubstance having the capacity to transmit light for illuminating aphotographic negative.

marcating plate.

LOUIS L. KROMHOLZ.

